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Malawi's new reality: Fall armyworm is here to stay

February 26, 2018

by Kimberly Keeton

By now, anyone with a link to agriculture in Africa has likely heard of the fall armyworm (FAW), a pervasive agricultural pest native to South and Central America that has ruthlessly worked its way across nearly the whole of the continent, after arriving in West Africa in early 2016 and making its way south of the Sahara and into Malawi by December of that same year. FAW has spread quickly due to its short reproductive cycle and ability to travel long distances quickly in the adult (moth) stage.

In Malawi, FAW poses a significant threat to smallholders and the nation’s food security as a whole, following a devastating cycle of natural disasters in the past two years. While FAW feeds on more than 80 plant species, including cash crops such as cotton in the country’s Salima district, its attack on staple crops sorghum, millet, and especially maize—Malawi’s primary staple crop and food source—is especially worrisome.

According to Jean-Pierre Busogoro, an agricultural scientist with the European Union delegation in Lilongwe, “a healthy crop resists pests better than a stressed crop.” Unfortunately, Malawi’s maize-dominated mono-cropping system—with its uniform plant tissues and populations—does not include the natural barriers that diverse, intercropped plant tissues have, making it vulnerable to aggressive pests like FAW that expand and flourish quickly.

Damage from FAW in Malawi has been significant. As of Feb. 1, estimates show that 382,000 hectares of maize, sorghum, and millet have been affected nationwide, impacting more than 1 million farm families, according to Albert Changaya, controller of Agriculture Extension and Technical Services at the Ministry of Agriculture, Irrigation and Water Development (MoAIWD). Roughly 10 percent of this years' dry season (non-irrigated) maize is expected to be lost to FAW, double last year's damage, MoAIWD data show.

Immediate response

Based on infestation rates, which vary across the country and have surpassed 80 percent in some hotspots, the Government of Malawi has prioritized pesticide distribution as an immediate response, and, along with development partners, has provided some pesticides for free to farmers. It is also providing training in pesticide use, as most smallholders have never used chemical pest control. According to the latest fourth Integrated Household Survey (IHS4), only 2.3 percent of all plots had either herbicides or pesticides applied in the 2015/16 agricultural seasons.

However, this approach has­ some limitations. The basic economics of pesticide use, according to George Phiri, an entomologist by training and assistant representative for programme at the Food and Agriculture Organization of the United Nations (FAO), indicate it is best to spray when at least 10 to 20 percent of plants are infested. Their efficacy can also vary considerably based on the timing and method of application, dilution rates, and the stage of its life cycle at which the pest is sprayed.

Phiri said that training is essential for farmers to scout their fields and assess the severity of the damage, and make their own decisions about how best to handle the pest. The government’s distribution program is limited, so in many cases, that won’t be with pesticides—the cost of which is generally prohibitive for smallholders.

The possible environmental and health risks of chemical control of FAW are another downside. Not only is applying pesticides costly, but it is potentially dangerous for people and the environment.

In addition to the procurement and distribution of pesticides, much of the initial FAW response has focused on creating awareness among farmers, extension workers, and supporting agencies. Farmers are being deluged with sometimes contradictory information. For those who do use chemicals—whether purchased from agrodealers, distributed for free, or subsidized by the government and NGOs—many receive different messaging on how to apply them, leaving plenty of room for human error, meaning chemicals may be misapplied and workers exposed.

According to Dimitri Giannakis of Farmers World, one of the largest suppliers of farm inputs in Malawi, most formal and informal agrodealers are not specifically trained in helping farmers choose the best pest control approach, nor are they able to evaluate the relative effectiveness of the chemicals they sell. In response, Farmers World created a Farm Services Unit to train formal agrodealers in their network to properly advise farmers and to help them weigh the costs and benefits of spraying.

Moving beyond the short term

While chemical pesticides certainly have a place in the immediate response, these problems illustrate the dangers of relying on pesticides alone. So the government has a plan for large-scale adoption of an Integrated Pest Management (IPM) approach, which combines its near-term emergency measures with longer-term strategic approaches.

“There is no single solution for FAW control,” Busogoro said. “We need to understand the interaction between pest and crop, and we need an integrated strategy,” to promote a healthy, resilient, and nutrient-rich crop environment containing pests’ natural enemies.

In the longer term, an IPM strategy is affordable and accessible for the majority of farmers. It can also help deliver consistent messaging on best agricultural practices. Busogoro favors working through farmer field schools (FFS) to address pest management because it is a participatory extension approach that involves farmers in both technology development and assessment as well as ‘’learning-by-doing.”

Adoption of good agronomic practices, including timely planting before FAW populations build up, is an integral part of dealing with FAW in the long term, Phiri said. He stresses the need to promote vigorous early plant growth coupled with early detection and treatment of FAW, as the older a crop gets, the lower the chances of successful pest control.

The use of intercropping and more diverse cropping systems can also help slow the spread of FAW and other pests and diseases by providing a barrier of non-compatible plant tissues that may not be edible to the pest, Busogoro said.

One intercropping technique that has proven particularly successful in controlling FAW is the “push-pull” approach. Originally developed to control the cereal stemborer, another pervasive pest, push-pull involves intercropping a cereal crop (like maize) with insect-repellent legumes of the Desmodium genus, along with an appealing forage plant, like Napier grass. The legume repels or “pushes” pests away from the primary cereal crop while the grass serves as an enticing border that “pulls” them away.

A push–pull field showing maize intercropped with silverleaf desmodium and with Napier grass planted as a border crop (left); climate-adapted push–pull field showing sorghum intercropped with drought tolerant greenleaf desmodium and Brachiaria cv mulato II as a border crop (right).

Learning from neighboring countries’ control methods for the stemborer as well as successful local control of African armyworm (from the same genus Spodoptera as FAW) can be useful. Since 2014, the Malawi government has worked with FAO to build capacity at the community-level to monitor and predict outbreaks of African armyworm in hotspots. The system is considered effective and can serve as a model for FAW monitoring and early warning.

The MoAIWD also plans research on various other solutions, such as understanding the impacts of conservation agriculture on FAW population dynamics and damage, and the development of local capacity for FAW biological control using effective parasitoids and predators, although they currently lack the necessary funds to do so.

Sometimes, less is more. The simpler and more accessible a solution is, the more likely it is to be taken up and sustained in the long term, well after external funds and subsidies cease. As Busogoro suggests, FAW—and other pests and diseases—can ultimately be neutralized if we focus on “simple technologies, adapted and accessible for the majority of farmers.”

As the world faces growing stresses on natural resources from climate change, population growth, urbanization, and other forces, researchers must grapple with complex questions about sustainable agriculture.